4. SCHC Compound ACK Example

Figure 7 shows an example transmission of a SCHC Packet in ACK-on-Error mode using the SCHC Compound ACK. In the example, the SCHC Packet is fragmented in 14 tiles, with N=3, WINDOW_SIZE=7, M=2, and two lost SCHC fragments. Only 1 SCHC Compound ACK is generated.

       Sender                Receiver
         |-----W=0, FCN=6 ----->|
         |-----W=0, FCN=5 ----->|
         |-----W=0, FCN=4 ----->|
         |-----W=0, FCN=3 ----->|
         |-----W=0, FCN=2 --X   |
         |-----W=0, FCN=1 ----->|
         |-----W=0, FCN=0 ----->| Bitmap: 1111011
     (no ACK)
         |-----W=1, FCN=6 ----->|
         |-----W=1, FCN=5 ----->|
         |-----W=1, FCN=4 ----->|
         |-----W=1, FCN=3 ----->|
         |-----W=1, FCN=2 ----->|
         |-----W=1, FCN=1 --X   |
         |-- W=1, FCN=7 + RCS ->| Integrity check: failure
         |<--- Compound ACK ----| [C=0, W=0 - Bitmap:1111011,
         |-----W=0, FCN=2 ----->|        W=1 - Bitmap:1111101]
         |-----W=1, FCN=1 ----->| Integrity check: success
         |<--- ACK, W=1, C=1 ---| C=1
       (End)

Figure 7: SCHC Compound ACK Message Sequence Example

|--- SCHC ACK Header --|- W=00 --|----- W=01 -----|
       |--T-|---M--|-1-|         |---M--|         |---M--|
+------+----+------+---+---------+------+---------+------+-----+
|RuleID|DTag| W=00 |C=0| 1111011 | W=01 | 1111101 |  00  | pad |
+------+----+------+---+---------+------+---------+------+-----+
                        next L2 Word boundary ->|<-- L2 Word ->|

Figure 8: SCHC Compound ACK Message Format Example: Losses are Found in Windows 00 and 01

4. SCHC Compound ACK Example​

4. SCHC Compound ACK Example